The present invention relates to a laser-scan process and device for guiding a missile to a target.
Although not exclusively, the invention applies more particularly to the guiding of a missile from a firing post, comprising the laser beam projector, an optical receiver being carried on board said missile.
The laser beam projector emits a radial scanning pattern intended to cover the whole of the missile guidance field. It is associated with a direct optical pathway (or any other televisual or thermal optical observation channel).
This arrangement has the drawback, the laser beam scanning the whole of the field, that said beam is then liable to be detected, and the firing post possibly destroyed by the adversary.
The aim of the invention is to reduce the eventuality of detection of the laser beam.
To this end, the laser-scan process for guiding a missile to a target, according to which one observes a field, within which said missile is liable to move, so as to locate the latter in said field, is noteworthy, according to the invention, in that, in said field, a zone is determined around the instantaneous position of said missile thus located, and in that the laser scan is performed solely in said zone.
Thus, the probability of detection of the laser beam is reduced as a function of the reduction in the xe2x80x9csurface areaxe2x80x9d scanned by said beam.
Although one could envisage now scanning only said zone (laser on) while excluding the remainder of the field, it is advantageous (essentially for practical reasons of adaptation of existing systems) that, the scan proper being performed throughout said field, the turning on of said laser beam coincides with the scanning of said zone.
In this case, the xe2x80x9cscanxe2x80x9d continues to be performed throughout the field, in essence with the laser beam off, the latter only being on, and hence possibly pinpointable, in the specified zone (appreciably reduced with respect to said field) around the instantaneous position of the missile, and the extent of which will depend on various parameters, which vary as a function of the missile firing conditions.
For the implementation of the above process, the invention also relates to a laser-scan device for guiding a missile to a target, comprising:
means for emitting a laser beam intended for transmitting flight control commands to said missile,
means for observing a field within which said missile is liable to move, so as to locate the latter in said field, and
means for scanning said field with said laser beam, which are linked to said emitting means,
noteworthy according to the invention by:
means for defining a zone around the instantaneous position of said missile in said field, which are linked to said observing means, and
means for activating said laser beam in said zone, which are linked to said means defining said zone.
Advantageously, said means of activating the laser beam are means for turning on said beam in phase with the means for scanning said field so as to make the turning on of said beam coincide with the scanning of said zone.
More particularly, the reduction in detectability of the laser beam is thus achieved by turning on the laser in such a way as to cover only that part of the guidance field in which the missile is to be found.
Advantageously, said observing means comprise a video camera, a semitransparent plate then being able to be interposed in the optical path between the viewfinder and the camera.
Preferably, a monitor allows the visualization of said zone in said field.
Either said monitor shares, with said camera, the same semitransparent plate interposed in said optical path, or said camera and said monitor are offset, and are associated, each, with their own semitransparent plate.
Preferably, a switch makes it possible to go from the laser scanning of said zone to the scanning of said field, when commanded by the operator, this being so as to again locate the missile should the latter leave said zone.
The figures of the appended drawing will elucidate the manner in which the invention may be embodied. In these figures, identical references denote similar elements.